Search

• The synergistic effect between MnO x and CrO x on 4%Cr 0.5 Mn 0.5 /AC boosted oxygen vacancies formation and active oxygen evolution. • The interaction relationship between toluene removal and Hg0 removal was elucidated. • Effect of flue gas components was explored to fulfill the industrial application. • A possible mechanism for the simultaneous removal of toluene and Hg0 was proposed by In-situ DRIFTS. In this study, a string of Cr-Mn co-modified activated coke catalysts (XCr y Mn 1-y /AC) were prepared to investigate toluene and Hg0 removal performance. Multifarious characterizations including XRD, TEM, SEM, in situ DRIFTS, BET, XPS and H 2 -TPR showed that 4%Cr 0.5 Mn 0.5 /AC had excellent physicochemical properties and exhibited the best toluene and Hg0 removal efficiency at 200℃. By varying the experimental gas components and conditions, it was found that too large weight hourly space velocity would reduce the removal efficiency of toluene and Hg0. Although O 2 promoted the abatement of toluene and Hg0, the inhibitory role of H 2 O and SO 2 offset the promoting effect of O 2 to some extent. Toluene significantly inhibited Hg0 removal, resulting from that toluene was present at concentrations orders of magnitude greater than mercury's or the catalyst was more prone to adsorb toluene, while Hg0 almost exerted non-existent influence on toluene elimination. The mechanistic analysis showed that the forms of toluene and Hg0 removal included both adsorption and oxidation, where the high-valent metal cations and oxygen vacancy clusters promoted the redox cycle of Cr3+ + Mn3+/Mn4+ ↔ Cr6+ + Mn2+, which facilitated the conversion and replenishment of reactive oxygen species in the oxidation process, and even the CrMn 1.5 O 4 spinel structure could provide a larger catalytic interface, thus enhancing the adsorption/oxidation of toluene and Hg0. Therefore, its excellent physicochemical properties make it a cost-effective potential industrial catalyst with outstanding synergistic toluene and Hg0 removal performance and preeminent resistance to H 2 O and SO 2. [Display omitted] [ABSTRACT FROM AUTHOR]

Abstract Mixed matrix membranes (MMMs), an important class of organic-inorganic nanocomposite membranes, were developed to overcome some of the limitations of purely polymeric membranes. In this study to improve the separation performance of polyvinyl chloride (PVC) membranes, mixed matrix membranes (MMMs) were prepared from incorporating choline prolinate based ionic liquid (IL) in a the coke/metal-organic framework (MOF) (NH2-MIL-101(Cr)) as a filler in polyvinyl chloride (PVC), which can be viewed as a potential solution to the trade-off problem with polymeric membranes because of the combination of the processing versatility of polymers and the high gas separation capability. Coke/MOF/PVC and IL@AC/MOF/PVC MMMs with different filler loadings of 5, 10, and 15 wt% were prepared using solution casting method and characterized using Fourier Transform Infrared Spectroscopy (FTIR), Thermogravimetric Analysis (TGA), Scanning Electron Microscopy (SEM) with Energy-Dispersive X-ray Spectroscopy (EDX) analyses, and Brunauer-Emmett-Teller (BET) surface area test. The porous structure of MMMs nanocomposites causes to which coke/MOF composite effectively accelerate gas diffusion in the PVC matrix. The permeability date was measured at 288.15, 298.15, 308.15 and 318.15 K and pressure up to 4 bar for CO2 and N2. According to the outcome, the addition of the IL([Cho][Pro]) filler, the permeability of the AC/MOF/PVC MMMs is increased compared to the pure PVC membrane. The MMMs have the highest gas separation efficiency and performance above Robson’s Upper Bound from 2008.

Mixed matrix membranes (MMMs), an important class of organic-inorganic nanocomposite membranes, were developed to overcome some of the limitations of purely polymeric membranes. In this study to improve the separation performance of polyvinyl chloride (PVC) membranes, mixed matrix membranes (MMMs) were prepared from incorporating choline prolinate based ionic liquid (IL) in a the coke/metal-organic framework (MOF) (NH2-MIL-101(Cr)) as a filler in polyvinyl chloride (PVC), which can be viewed as a potential solution to the trade-off problem with polymeric membranes because of the combination of the processing versatility of polymers and the high gas separation capability. Coke/MOF/PVC and IL@AC/MOF/PVC MMMs with different filler loadings of 5, 10, and 15 wt% were prepared using solution casting method and characterized using Fourier Transform Infrared Spectroscopy (FTIR), Thermogravimetric Analysis (TGA), Scanning Electron Microscopy (SEM) with Energy-Dispersive X-ray Spectroscopy (EDX) analyses, and Brunauer-Emmett-Teller (BET) surface area test. The porous structure of MMMs nanocomposites causes to which coke/MOF composite effectively accelerate gas diffusion in the PVC matrix. The permeability date was measured at 288.15, 298.15, 308.15 and 318.15 K and pressure up to 4 bar for CO2 and N2. According to the outcome, the addition of the IL([Cho][Pro]) filler, the permeability of the AC/MOF/PVC MMMs is increased compared to the pure PVC membrane. The MMMs have the highest gas separation efficiency and performance above Robson's Upper Bound from 2008. [ABSTRACT FROM AUTHOR]

Simultaneous desulfurization and denitration by using activated coke is one of the most competitive technologies for cleaning low-temperature steel flue gases. The key to denitration performance relies on the regulation of active groups on the catalyst. In this work, the carboxyl and lactone groups with (NH4)2S2O8 oxidation and thermal treatment were found to mainly determined the catalytic activity. The results showed that (NH4)2S2O8-treated AC catalyst improved denitration activity at low temperatures, which was attributed to the increase in oxygen-containing groups of the AC, the thermal treatment enhanced the low-temperature activity while reduced the performance in (210–240 ℃). According to the characterization results and conformational relationship analysis, we revealed that the adsorption and activation of NH3 mainly depended on carboxyl groups during the middle-temperature range (210–240 ℃) NH3–SCR. Based on the advantage of middle-temperature denitration activity of modified activated coke, the carboxyl groups on activated coke were the most important active sites for the NH3–SCR reaction. Moreover, lactone groups, improved the denitration performance via promoting NO oxidation at low-temperatures range (120–150 ℃). However, the presence of only lactone groups in the 210–240 ℃ is not beneficial for the further promotion for denitration activity. This work initially reveals the decisive role of carboxyl and lactones groups of activated coke for the low-temperature NH3-SCR reaction, and guides the industrial arrangement of oxidation-modified AC as denitration catalyst. [ABSTRACT FROM AUTHOR]

Activated coke is a type of commonly used adsorbent for benzene series VOCs such as toluene, but traditional microporous activated coke usually faces the challenge of poor regeneration performance. Herein, based on self-made activated cokes with typical pore configuration, we found that adsorption and regeneration of toluene can be simultaneously enhanced by constructing hierarchical pore in activated coke. Correlations of pore configuration with toluene adsorption capacity and regeneration efficiency reveal that micropore contributes for strong toluene adsorption; meso-macropore provides mass transfer channel for toluene desorption and regeneration process. Hierarchical porous activated coke prepared from Zhundong subbituminous coal not only achieves the highest toluene adsorption capacity of 340.92 mg·g−1, but also can retain more than 90% of initial adsorption capacity after five adsorption-regeneration cycles. By contrast, micropore-dominant activated cokes can only retain 70% of initial adsorption capacity. Adsorption kinetic modelling on adsorption breakthrough curves shows that hierarchical porous activated coke prepared from Zhundong subbituminous coal exhibits high adsorption and diffusion rate constants of 14.39 and 33.45 min−1, respectively, much higher than those of micropore-dominant activated cokes. Due to the accelerated surface adsorption and diffusion processes induced by meso-macropore, toluene adsorption and regeneration behavior can be simultaneously improved. Results from this work validated the role of pore hierarchy in toluene adsorption-regeneration process, providing guidance for designing high-performance activated coke with synergistically improved toluene adsorption capacity and regeneration performance. [ABSTRACT FROM AUTHOR]

Mn oxides are confined within the porous structure of activated coke (ACO) via impregnation followed by calcination treatment. The Mn-ACO sample calcined at 600 °C (Mn-ACO600) demonstrated superior performance despite containing only a minute atomic ratio of 0.11 % Mn on its surface. This treatment led to a slight increase in the specific surface area and pore volume of ACO, with a significant enhancement in the proportion of micropores, rising from 54.2 % in ACO to 71.8 % in Mn-ACO600. Raman spectroscopy indicated additional defects in Mn-ACO, while XPS analysis confirmed the coexistence of Mn(II), Mn(III), and Mn(IV) oxides. Although ACO adsorption alone was ineffective in removing acesulfame (ACE), Mn-ACO600 achieved a removal rate of 19.0 %. The introduction of peroxydisulfate (PDS) further boosted the degradation of Mn-ACO600, with a Kapp value that was 2.28 times of that of the combined Mn-ACO600 adsorption and PDS oxidation process, indicating a remarkable synergistic effect. To optimize the experimental conditions, a response surface methodology design analysis was conducted, revealing that solution pH and the dosage of Mn-ACO600 were crucial factors. Furthermore, the study confirmed non-radical oxidizing species, such as 1O2 and h+, played a predominant role in the process, with relatively minor contributions from radical oxidizing species.

The massive release of mercury undermines environmental sustainability, and with the official entry into force of the Minamata Convention, it is urgent to strengthen the control of mercury pollution. The effectiveness of activated coke (AC) in removing elemental mercury (Hg0) from high temperatures and sulfur nonferrous smelting flue gas before acid production was studied. Experimental results indicated that the optimal temperature for Hg0 adsorption by AC was 150 °C. And the adsorption of Hg0 by AC was predominantly attributed to physical adsorption. Flue gas components (SO2 and O2) impact studies indicated that O2 did not significantly affect Hg0 adsorption compared to pure N2. Conversely, SO2 suppressed the adsorption capacity, while the simultaneous presence of SO2 and O2 exhibited a synergistic effect in facilitating the removal of Hg0. The characterization results of X-ray photoelectron spectroscopy (XPS) indicated that the SO2 molecule favored to anchor at the Oα site, leading to the formation of SO3. This subsequently oxidized the mercury to HgSO4 instead of HgO. The study demonstrates that cheap and easily accessible AC applications in the adsorption of mercury technology may help improve the sustainability of the circular economy and positively impact various environmental aspects. [ABSTRACT FROM AUTHOR]

The adsorption of phenol (Ph), 4-chlorophenol (CP), and 4-cresol (MP) from aqueous solutions on three carbonaceous materials of diverse origins but similar specific surface areas was investigated. Vulcan XC72 carbon black (CB), AKP-5 activated coke (AC), and activated tire pyrolysis char (AP) were examined as adsorbents. The kinetics and equilibrium adsorption, as well as the influence of pH and ionic strength of each solution on the adsorption process, were studied. The results revealed that the adsorption was pH-dependent and preferred an acidic environment. The presence of an inorganic salt in the solution (ionic strength) did not affect the adsorption processes of the three adsorbates. The pseudo-first- and pseudo-second-order equations, as well as the Weber–Morris and Boyd kinetic models, were used to describe the adsorption kinetics. It was found that equilibrium was reached for all adsorbates after approximately 2–3 h. Adsorption kinetics followed a pseudo-second-order model, and the adsorption rate was determined by film diffusion. The adsorption isotherms were described using the Langmuir and Freundlich equations. The results revealed that the adsorption processes of Ph, CP, and MP on all three adsorbents from the water were better described by the Langmuir model. The adsorption of CP was the most efficient, the adsorption of MP was slightly weaker, and the adsorption of phenol was the least efficient. [ABSTRACT FROM AUTHOR]

Both sludge biochar (BC) and activated coke (ACO) are hierarchical while their surface properties have a large disparity. We show that sludge biochar pyrolyzed at 600°C (BC600) outperforms biochar produced at other temperatures for a range of biomass feedstock. BC600 displays lower carbon content, lower surface area, and importantly more abundant surface oxygen-containing functional groups when compared with ACO. BC600 and ACO were used to activate peroxydisulfate (PDS) for tetracycline oxidation while the degradation mechanisms were comprehensively discussed. Interestingly, ACO demonstrated a particularly higher performance where activating PDS compared with BC600. The Kapp value for the synergetically combined ACO-PDS process was 2.15 times that of the sum of adsorption and PDS oxidation processes alone, while it was 1.72 times for the BC600-PDS process. Solution pH had a more dramatic influence on BC600 than on ACO. Quenching experiments proved that both OH• and SO4 •-contributed insignificantly while most of the degradation was attributed to superoxide radical (O2 •-), singlet oxygen (1O2), and active holes (h+). After reducing carbonyl groups on both carbons by KBH4 in absolute alcohol, quenching experiments did not indicate the key role of carbonyl groups for 1O2 generation. Nonradical pathway proved dominant in the carbon/PDS catalytic process. Excellent reusability and stability for ACO was observed in repeated use experiments. [ABSTRACT FROM AUTHOR]

[Display omitted] • Rapid heating achieves coupling of regeneration and reduction reactions. • The adsorbed SO 2 effectively desorbs during rapid heating. • Desorbed SO 2 was further reduced by carbon to elemental sulfur. • Carbothermal reduction optimized the carbon texture characteristics. • The performance of regenerated coke was restored or even optimized. Current advancements in flue gas desulfurization have highlighted the efficacy of activated coke (AC) as an SO 2 adsorbent, leveraging sulfur resources. Despite its success, challenges such as lengthy processing and logistics for sulfuric acid storage and transport limit its widespread use. This research explores an innovative approach: powder saturated AC (SAC) achieves rapid temperature rise and one-step regeneration coupled reduction in a drop-tube reactor. Findings reveal that SAC undergoes primary regeneration at 450–650 ℃, converting adsorbed sulfur compounds into gaseous SO 2. However, issues like incomplete active site recovery and surface oxidation reduce the re-adsorption capacity of regenerated AC. At 750–950 ℃, a concurrent regeneration and reduction phase converts desorbed SO 2 into elemental sulfur. Carbothermal reduction during this phase enhances microporous structure development, lowers oxygen content, increases edge defects, promotes sulfur doping, and boosts SO 2 re-adsorption efficiency. This study provides practical insights and a conceptual framework to refine desulfurization processes and optimize resultant products. [ABSTRACT FROM AUTHOR]

[Display omitted] • The research progress on pollutant removal by activated coke is summarized. • Hierarchical porous structure favors synergistic removal of pollutants. • Oxygen-containing functional groups facilitate the removal of SO 2 , NO and PCDD/Fs. • Metal modified activated coke has better ability to remove pollutants. Activated coke has been widely used in the flue gas purification process due to its well-developed pore structure, abundant surface functional groups, good mechanical strength, and excellent regeneration properties. This paper presents a comprehensive overview of the mechanisms involved in the efficient removal of SO 2 , NOx, Hg0, and PCDD/Fs from flue gas through the utilization of activated coke. The impact of surface area, pore structure, and functional groups of activated coke on the purification of pollutants was thoroughly reviewed. The impact of flue gas composition and temperature on the mitigation of pollutants was succinctly elucidated. The modification methods and effects of activated coke were summarized. The regeneration techniques and characteristics of adsorbed saturated activated coke are also presented. It provides reference for parameter optimization, process improvement and synergistic removal of pollutants in activated coke process. [ABSTRACT FROM AUTHOR]

In this work, toluene removal by activated coke (ACK) was investigated. For the first time, metal-free carbon catalytic oxidation of toluene on ACK was experimentally demonstrated. On this basis, the active sources of carbon catalytic oxidation of toluene on ACK, including surface defects, pore grading degree (V m e s + m a c /V t), and surface oxygen functional groups, were identified in combination with characterization tests. The catalytic effects of different oxygen-containing functional groups (C=O, COO-, C-O-) on toluene oxidation were analyzed. The carbon catalytic oxidation reaction path of toluene on ACK has been determined as follows: toluene → benzyl alcohol → benzaldehyde → benzoic acid → maleic anhydride → carbon dioxide and water. It can be divided into three steps: initial oxidation of toluene to benzyl alcohol and benzaldehyde on C=O; deep non-mineralized oxidation of benzyl alcohol and benzaldehyde on C=O, COO-, C-O-; and mineralized oxidation of intermediate products on C-O- to produce CO 2. The gradual oxidation of toluene promotes the interconversion of C=O, COO-, and C-O-, with the assistance of O 2 and reactive oxygen species (O ∗) generated by activation of O 2 and adsorbed water. [Display omitted] • The metal-free carbon catalytic reaction of toluene on activated coke was confirmed. • Meso/macro-pore, defect, and oxygenated functional group facilitate toluene removal. • C=O promotes toluene partial oxidation, and C-O- facilitates CO 2 production. • O 2 and H 2 O a d participate in toluene oxidation, with C-O- ⇌ C=O ⇌ COO-. [ABSTRACT FROM AUTHOR]

Activated coke was obtained by CO2 activation with disused fine blue-coke serving as the main raw material and direct coal liquefaction residue (DCLR) as binder. The effect of the dosage and activation temperature of DCLR on the compressive strength of active coke and desulfurization were mainly investigated. The experimental results showed that the compressive strength of the activated coke increased first and then decreased with the increase in the amount of D-DCLR (DCLR after ash removal). When the amount of D-DCLR was 40%, the compressive strength of the activated coke was 492.55 N and the specific surface area was the highest (189.78 m2·g−1) among other samples. The results show that the activated coke has a high removal rate for low concentrations of sulfur dioxide. This work provides a way for efficient utilization of DCLR, which avoids waste of resources and environmental pollution. In addition, it is important for finding green and efficient blue-coke powder processing and utilization technology for the sustainable development of the blue-coke industry.

Despite immense research efforts in the field of Au supported on carbon matrix, the rational design and fabrication of ultrafine Au/carbon matrix nanocatalysts with effective reactivity and high stability are still challenging. The main obstacles are faced with adjusting the size of Au nanoclusters and strengthening the bond of Au and carbon. In this work, sulfonate groups (−SO 3 H) introduced onto activated coke (AC) matrix was prepared for steadily anchoring ultrafine Au nanoclusters (∼2 nm). The obtained Au/SO 3 H-AC exhibited superior reactivity for 4-nitrophenol reduction within 3 min using NaBH 4 as reducing agent. The superior performance and stability are attributed to the − SO 3 H groups with hydrophilic property, benefiting for substrates readily dispersion and for Au species (including oxidized Au+ and Au3+) bind and stabilization, possibly by tightly interacting with the O atoms bound to S atom of − SO 3 H. In addition, several lines of evidence demonstrate the oxidized Au species can serve as electron relay system, ensuring the sustained reaction. Given that the Au nanoclusters in this study have superior reactivity and stability, this work proposes a novel strategy for preparing other supported metal nanocomposites. [ABSTRACT FROM AUTHOR]

SO2 and NOx in flue gas are serious environmental pollutants. As an excellent adsorbent, activated coke has good application potential in flue gas desulfurization and denitrification. In this study, different concentrations of NH3 and K2CO3 solutions were used to modify the activated coke made from biomass and coal, and then separate and coordinated desulfurization and denitrification experiments were carried out. The adsorption efficiency of activated coke and the adsorption capacity of SO2 and NO were compared, and the adsorption relationship between SO2 and NO was clarified. The changes of the surface functional groups of activated coke before and after adsorption and the forms of SO2 and NO after adsorption were analyzed by Fourier transform infrared spectrometer and X-ray diffractometer patterns. Results show that K2CO3 and NH3 modification can promote the adsorption of SO2 and NO in activated coke, and K2CO3 modification is more significant for improving the denitrification and desulfurization capacity. When the unmodified activated coke synergistically adsorbs SO2 and NO, there is a competitive adsorption between NO and SO2. However, when the activated coke modified with K2CO3 solution and NH3 synergistically adsorbs SO2 and NO, both have a promoting effect. After the adsorption of NH3-modified activated coke, CaSO4 and Na2SO4 crystals will appear. K2SO4 will exist after the adsorption of activated coke modified with K2CO3 solution. [ABSTRACT FROM AUTHOR]

Simultaneous removal of Hg0 and H2S over a regenerable activated coke supported Fe2O3 catalyst (Fe2O3/AC) was studied in simulated coal-derived syngas. It was found that the Fe2O3/AC catalyst exhibited high capability for Hg0 and H2S removal, which was attributed to the catalytic oxidation activity of Fe2O3. Its capability for Hg0 and H2S removal increased with an increase of Fe2O3 loading amount, and the highest was at 150 °C for Hg0 removal. CO and H2 showed no obvious effect on Hg0 removal by Fe2O3/AC, while H2S had a promotion effect, which was due to S and FeSx produced by the H2S reaction on Fe2O3/AC. The results of SEM-EDX and the temperature programmed desorption experiment (TPD) revealed that Fe2O3 played a critical role in Hg0 oxidation, and HgS was generated upon the reaction of Hg0 with H2S on Fe2O3/AC. The used Fe2O3/AC catalyst after Hg0 and H2S removal could be effectively regenerated and still had high capability for Hg0 and H2S removal. [ABSTRACT FROM AUTHOR]

Activated coke-based catalysts have attracted extensive attention in denitration by selective catalytic reduction by NH3 (NH3-SCR), due to their excellent catalytic performance at low temperature. In the paper, the V2O5/AC catalyst was prepared by the impregnation method to investigate the effect of pre-oxidation process on its NH3-SCR activity. Activity test results show that the V2O5/AC catalyst with 4-h pre-oxidation exhibits the best NOx removal efficiency, which reaches the NOx conversion is over 75% in the range of 200–240 °C and exhibits an excellent resistance to SO2 and H2O. Characterization results demonstrate that the V4+ was oxidized by oxygen molecule during pre-oxidation process, which contributes to the formation of V5+ ions and surface-active oxygen species. The surface-active oxygen species are conducive to promoting the "fast SCR" reaction; thus, the pre-oxidized process can contribute to the superior NH3-SCR performance for V2O5/AC catalyst at low temperature. [ABSTRACT FROM AUTHOR]

The low temperature of sintering flue gas limits the application of common vanadium‐ and titanium‐based catalysts if flue gas is not reheated. In this study, cylindrically molded activated coke was prepared from steel slag and coke powder of an iron and steel plant for low‐temperature denitration. The fraction of activated coke precursor and activation conditions were optimized by orthogonal experiments and the response surface method, respectively. Denitration tests on low‐temperature simulated sintering flue gas and characterization of the physical and chemical properties of the activated coke were carried out. Fe2O3 of steel slag showed catalytic reductive activity. [ABSTRACT FROM AUTHOR]

This article discusses the desulfurization and denitrification integrated purification technology for activated coke. This technology has been widely used in globally due to its ability to simultaneously remove NOx, SO2, dioxin, and dust from the flue gas. The approach discussed adopts a cross‐flow method in which the activated coke flows from the top to the bottom in the adsorption tower, and the flue gas passes through the activated coke bed horizontally from the side. To create a more economically appealing solution, the waste heat recovery system is optimized and a regeneration gas processing system is added to recycle the gas with a high concentration of SO2. In this process, first desulfurization and then denitrification. The denitrification process is performed by selective catalytic reduction of NOx with NH3 reaction (NH3‐SCR). The results show that under the flue gas condition (NOx = 300 mg/Nm3 and SO2 = 200 mg/Nm3), SO2 is almost completely removed and the NOx removal efficiency is greater than 80%. After SO2 adsorption, the activated coke can be regenerated in a regeneration furnace at 400–450°C and the highly concentrated SO2 produced during the regeneration process can be further used for the production of ammonium sulfate. The purpose of the regeneration reaction of activated coke is to reactivate and recover the activated coke. Finally, the cost analysis results of the system show that the desulfurization and denitrification integrated purification technology for activated coke has excellent economic benefits. [ABSTRACT FROM AUTHOR]

Abstract In order to study the mechanism of selective catalytic reduction of activated coke to remove NO in low-temperature flue gas and provide some theoretical basis for the development of related technologies. The pore size distribution and BET specific surface area of AC were obtain by data analyzing of N2 adsorption/desorption isotherm at − 196 °C and carbon matrix and surface chemistry of virgin activated coke samples were characterized by acid–base titration and XPS. The process of selective catalytic reduction of activated coke (AC) samples with NH3 as reducing agent was studied in a fixed bed reactor at 150 °C. The result shows that pore size distribution or BET specific surface of activated cokes have not correlation with denitrification activity for SCR. The NO reduction activities of the activated cokes are apparent to increase with their surface oxygen element content and total amount of acidic sites. Obviously there is good linear relationship between the NH3 adsorption capacity and activity for SCR with linear correlation coefficient 0.943. It has been presented that adsorption of NH3 on acidic functional groups in the edge of large polycyclic aromatic ring of activated coke is key rate controlling step in the SCR heterogeneous catalytic reaction.

The advanced treatment of printing and dyeing wastewater by adsorption using activated coke was studied. Specifically, the effects of adsorption conditions on wastewater treatment were examined by adsorption experiments. Meanwhile, the adsorption behaviors of organic pollutants by activated coke were investigated by the adsorption kinetics and isotherms. The chemical oxygen demand (COD) removal met the printing and dyeing wastewater discharge requirement under the conditions of initial COD concentration 158 mg/L, adsorption time 360 min, activated coke concentration 30 g/L and adsorption temperature 308 K. After adsorption, 53.86% of COD was removed. The adsorption kinetics of COD by activated coke followed the pseudo-second-order model and the adsorption isotherms could be expressed by the Freundlich model. Moreover, thermal regeneration of spent activated coke was studied. Specifically, the effects of regeneration conditions on the thermal regeneration efficiency of spent activated coke were examined by thermal regeneration experiments. Meanwhile, the reusability of activated coke for organic pollutants removal was evaluated by the successive adsorption-regeneration cycles. 98.13% of thermal regeneration efficiency could be achieved under the conditions of regeneration temperature 1,073 K, regeneration time 30 min and CO2 flow rate 150 mL/min, and activated coke still maintained 92.54% of regeneration efficiency after ten adsorption-regeneration cycles. [ABSTRACT FROM AUTHOR]

Copyright of Chinese Journal of Applied Ecology / Yingyong Shengtai Xuebao is the property of Chinese Journal of Applied Ecology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

• Cu-CoOx/AC N were optimized for synergetic-catalysis removal of CO and Hg0 at low-temperature (<200 °C). • CoO ⇌ Co 3 O 4 and Cu 2 O ⇌ CuO were benefit for CO oxidation by Co– and Hg0 removal by Cu-species. • Hg0 removal followed the combination processes of adsorption and catalytic oxidation via L-H mechanism. • Catalysis-oxidation of CO to CO 2 abided by the Mars–van Krevelen mechanism with lattice oxygen species. Cu-Co multiple-oxides modified on HNO 3 -pretreated activated coke (AC N) were optimized for the simultaneous removal of gaseous CO and elemental mercury (Hg0) at low temperature (< 200 °C). It was found that 2%CuOx-10%CoOx/AC N catalyst calcined at 400°C resulted in the coexistence of complex oxides including CuO, Cu 2 O, Co 3 O 4 , Co 2 O 3 and CoO phases, which might be good for the simultaneous catalytic oxidation of CO by Co-species and removal of Hg0 by Cu-species, benefiting from the synergistic catalysis during the electro-interaction between Co and Cu cations (CoO ⇌ Co 3 O 4 and Cu 2 O ⇌ CuO). The catalysis removal of CO oxidation was obviously depended on the reaction temperature obtaining 94.7% at 200 °C, while no obvious promoting effect on the Hg0 removal (68.3%-78.7%). These materials were very substitute for the removal of CO and Hg° from the flue gas with the conditions of 8–20 vol.% O 2 and flue-gas temperature below 200 °C. The removal of Hg° followed the combination processes of adsorption and catalytic oxidation reaction via Langmuir-Hinshelwood mechanism, while the catalysis of CO abided by the Mars-van Krevelen mechanism with lattice oxygen species. Image, graphical abstract Synergetic-catalysis mechanisms for the oxidation of gaseous CO and Hg0 were proposed over Cu-CoOx/AC N catalyst, in which the removal of Hg° followed the combination processes of adsorption and catalytic oxidation reaction via Langmuir–Hinshelwood mechanism, while the catalysis of CO-to-CO 2 abided by the Mars–van Krevelen mechanism with lattice oxygen species. [ABSTRACT FROM AUTHOR]

Microwave modification of activated coke is reported as a green and simple route to improve its synergistic desulfurization and denitrification. The results showed that microwave irradiation improved the specific surface area and pore volume, decreased the pore size, and activated the surface functional groups of the activated coke. Under the conditions of a microwave power of 500 W and a modification time of 30 min, the specific surface area was increased from 185.9 m²/g to 351.7 m²/g, the pore volume increased from 0.042 m³/g to 0.111 m³/g, and the characteristic peak strengths of C=C and -OH drastically increased. When the reaction temperature was 140 °C and the O2 concentration was 10% (by volume), the desulfurization and denitrification efficiency were maintained at levels greater than 90% and 80% for 30 min and 15 min, respectively. The C-O content increased, and the C=C and -OH content decreased after undergoing desulfurization and denitrification. The desulfurization and denitrification products were primarily sulfate and nitrate. This provides theoretical support for the application of microwave modified active coke in low temperature desulfurization and denitrification. [ABSTRACT FROM AUTHOR]

The aim of this study was to study the influence factors of selective catalytic reduction (SCR) of NO with NH3 in flue gas and to clarify the mechanism of SCR over activated coke (AC). An AC in various simulated flue gases for reduction of NO was examined in a fixed-bed reactor. X-ray photoelectron spectroscopy (XPS) was used to performhigh-resolution scanning of surface N element. The results indicate that the presence of O2 in flue gas facilitates the NO reduction in SCR. Higher polarity of H2O molecule may inhibit NH3 or NO adsorption on the surface of ACs, so that NO reduction has been restrained. A lowest NO conversion was tested at 250°C in the temperature range of 100–350°C, meaning that may presence of different SCR mechanism at low or high temperature. Adsorption of NH3 below 250°C is dominated by physical adsorption and adsorption of NH3 higher than 250°C is dominatedby the chemical reaction between NH3 and AC base on the determination of XPS and adsorption capacities of NH3. There was a good correlation between adsorption capacity of NH3 and NO conversion, which indicated that NH3 adsorption is a key step in SCR regardless of whether NH3 was physically or chemically adsorbed on the AC. [ABSTRACT FROM AUTHOR]

In this study, Manganese oxide (MnO x) was supported on activated coke modified by (NH 4) 2 S 2 O 8 (ACs) to obtain novel MnO x /ACs catalysts with high NO x removal performance by excessive impregnation method. The influence of precursor and loading amount of MnO x on the catalytic efficiency were studied. The Mn 3 O 4 supported on ACs samples prepared with manganese acetate tetrahydrate as precursor and the loading amount of 8% Mn is the most effective in NO x removal among modified samples and its removal efficiency is 97% at 180 °C. And the adsorption state and reaction behaviors of NH 3 , NO and O 2 on MnO x /ACs catalysts were measured by in situ diffuse reflectance infrared Fourier transform spectroscopy (in situ DRIFTS) in different conditions in order to study the effect of MnO x and the reaction mechanism. The results suggested that Eley-Rideal and Langmuir-Hinshelwood mechanism existed simultaneously for the selective catalytic reduction of NO over the MnO x /ACs catalyst. Image 1 • High efficiency of DeNO x catalyst was formed by Mn 3 O 4 loaded on active coke. • The best precursor agent and loading amount were discussed. • The mechanism of the reaction occurred on the catalyst was studied. [ABSTRACT FROM AUTHOR]

To develop a new process of sulfur recovery for activated coke desulfurization, reduction of sulfur dioxide by activated coke and pyrolysis gas from powder coke fast preparation system was studied experimentally and theoretically. The distribution of gas products in the experiment was measured by GC-MS analyzer and refinery gas analyzer, while the thermodynamic equilibrium data was calculated by the Factsage software. The activated coke presented great catalytic performance for SO 2 reduction by CO and H 2. The reactivity of CO reducing SO 2 was higher than that of H 2 , and the two gaseous reducing agents were independent of each other during the reaction process. The effect of CO 2 on SO 2 reduction was slight, while the participation of H 2 O resulted in a significant decrease in S yield. The unsteady state experiment shows that the catalytic ability of activated coke did not affect by reaction between carbon and SO 2 , CO 2 or H 2 O. • The coupling reduction of SO 2 with active coke and pyrolysis gas is effective. • Activated coke is used as both reducing agent and catalyst in the SO 2 reduction. • Reduction of SO 2 by CO and H 2 in activated coke bed is almost mutually independent. • CO 2 affects SO 2 reduction to elemental sulfur to a small degree. • The presence of H 2 O had a significant negative effect on the SO 2 reduction. [ABSTRACT FROM AUTHOR]

Low‐rank activated coke (AC) is widely used for industrial flue gas purification due to its multipollutant cooperative removal capability. To enhance the denitrification capacity of AC for the selective catalytic reduction (SCR) of NO with NH3, several transition metal (Fe, Mn, Ce, V) oxides were uniformly loaded into AC by solvent impregnation. Compared to untreated AC, modified AC showed excellent denitrification efficiency above 90%. N2 adsorption‐desorption and Raman spectroscopy techniques were used to characterize the pore size distribution and crystal structure of AC samples. The introduction of transition metal oxides had little effect on the pore structure of AC but increased the nitrogen‐containing functional groups, which facilitated NO removal. Moreover, x‐ray photoelectron spectroscopy (XPS) was used to analyze the valence changes of metal elements before and after denitrification. After the reaction, the content increase of the low‐valence metal oxides indicated that the transition metal oxides were involved in the reaction of NO with NH3. High‐valence metal oxides oxidized NO to NO2, which reacts more easily with NH3, thereby increasing the denitrification efficiency. Importantly, in the presence of SO2, modified AC still presented high denitrification performance. This transition metal oxides doping method can effectively improve the ability of low‐rank AC to remove NO in multi‐contaminant flue gas. [ABSTRACT FROM AUTHOR]

Impregnating CuCl2 on AC (activated coke) support to synthesize xCuCl2/AC showed superior activity with higher 90% Hg0 removal efficiency at 80–140 °C, as well as a lower oxygen demand of 2% O2 for Hg0 removal. The acceleration on Hg0 removal was observed for NO and SO2. The BET, SEM, XRD, XPS, TPD, and FT-IR characterizations revealed that the larger surface area, sufficient active oxygen species and co-existence of Cu+ and Cu2+ may account for the efficient Hg0 removal. In addition, the low demand of gaseous O2 was contributed to higher content of active oxygen and formed active Cl. After adsorbing on Cu sites, Cl sites, and surface functional groups, the Hg0(ads) removal on xCuCl2/AC was proceeded through two ways. Part of Hg0(ads) was oxidized by active O and formed Hg0, and the other part of Hg0 combined with the active Cl, which was formed by the activation of lattice Cl with the aid of active O, and formed HgCl2. Besides, the Hg2+ detected in outlet gas through mercury speciation conversion and desorption peak of HgCl2 and Hg0 further proved it. As displayed in stability test and simulated industrial application test, CuCl2/AC has a promising industrial application prospect. [ABSTRACT FROM AUTHOR]

To improve the denitrification efficiency for the selective catalytic reduction of NO with NH3 in the flue gas purification process, a low-rank activated coke (AC) was treated with ammonia (NH3·H2O) solution or nitric acid (HNO3) solution to increase the content and type of nitrogen-containing functional groups, and then the role of nitrogen-containing functional groups in the reduction of NO was analyzed. The modified AC samples were characterized by N2 adsorption/desorption to determine the pore structures and by Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy to detect the surface functional groups. After modification, the content of oxygen-containing functional groups on the AC surface increased, including quinone, lactone and carboxyl, which are favorable for SO2 adsorption. Meanwhile, the type and content of nitrogen-containing functional groups on the AC surface changed; these groups fall into two categories: active groups and non-active groups. Before and after the denitrification process, the regular changes in the content of active and non-active groups showed that the active groups with pyrrole-like or pyridine-like structures can promote NO adsorption and then strengthen the denitrification. On the other hand, active groups may be reduced by NH3 or oxidized by O2, referring to side reactions, to generate non-active groups such as nitro, nitrate, amine and imine. More importantly, the role of nitrogen-containing functional groups was identified in the denitrification process. This chemical modification method is effective for improving the performance of low-cost AC since the employed chemicals are commercially available. [ABSTRACT FROM AUTHOR]

Porous materials such as activated cokes have been widely utilized in the adsorption removal of atmospheric SO 2 emission. Pore configuration of coke is a key factor affecting its SO 2 rapid adsorption dynamics, which is critically important for fluidization adsorption craft. Herein, activated coke adsorbents with typically microporous structure and hierarchically porous structure were prepared by a catalytic physical activation method from Chinese large-reserve Zhundong coal, which were used as model adsorbents to investigate the effect of pore configuration on SO 2 fluidized adsorption dynamics. SO 2 fluidized-state adsorption experiments indicate that hierarchically porous coke has a more rapid initial adsorption dynamic than microporous type coke, and coke with 44.2% meso-/macropores volume shows the highest initial adsorption rate of 7.37 mg g−1·min−1. Additionally, the fitting of Weber-Morris model provides the dominate factors for SO 2 adsorption kinetics in each sub-process: SO 2 adsorption capacity of microporous-dominated adsorption stages account for 70%–80% of total, and when it comes close to adsorption saturation, the main dominant factor of kinetic becomes the ratio of meso-/macropores volume. This work is of significance for the application of SO 2 adsorption craft in fluidized bed and also provides insight into the role of hierarchically porous configuration in gas molecule rapid adsorption. Image 1 • Model adsorbents for investigating the effect of pore structure on adsorption dynamics are provided. • Hierarchically porous coke shows higher initial adsorption rate of SO 2 in fluidized bed. • Dominate factors of SO 2 adsorption dynamics in each sub-process are elucidated. [ABSTRACT FROM AUTHOR]

A significant amount of flue gas pollutants (SO 2 , NO x , Hg0, and VOCs) are produced with the growth of human industrial activities including thermal power generation and iron and steel metallurgy. Activated coke is a low-cost, high-efficiency adsorbent for the removal of pollutants. It is the foundational component of dry flue gas purification technology and is easily recycled. The preparation, activation, modification, and engineering applications of activated coke are discussed in this paper. The removal mechanism of SO 2 , NO x , Hg0, and VOCs on activated coke is also summarized, along with the related factors affecting the adsorption performance of activated coke. This review demonstrates that physical activation, chemical activation, and a variety of modification techniques (such as metal loading) can improve the surface pore structure, increase the number of active sites on the surface, and introduce new functional groups, thereby improving the ability to remove pollutants. Additionally, the impact of the adsorption conditions (gas composition, adsorption temperature) on the ability of the activated coke to remove pollutants is extensively covered in this work. Some examples of practical applications of activated coke are listed. This review will serve as a roadmap for future research and application of activated coke. [Display omitted] • The mechanism of pollutants removal by activated coke are introduced. • The methods of preparation, activation, modification of activated coke are reviewed. • The factors influencing the adsorption of pollutants by activated coke are overviewed. • The research and application of collaborative adsorption of pollutants are summarized. [ABSTRACT FROM AUTHOR]

Activated coke was prepared by CO2 activation using solid waste fine blue-coke as main raw material and coal direct liquefaction residue (DCLR) as binder. The activated coke was characterized by BET, XRD, and infrared analysis. The flue gas desulfurization experiment was carried out with a fixed bed reactor and activated coke as the adsorbent. The experimental results show that coal direct liquefaction residue pyrolysis process will produce a large number of cohesive colloids, further increasing the strength of the activated coke. BET analysis shows that there is abundant microporous structure in the activated coke, infrared analysis shows that the activated coke contains abundant surface functional groups, and XRD shows that the crystallization degree of the activated coke is high. At lower temperature, SO2 and O2 have competitive adsorption on the surface of activated coke, if the concentration of water vapor is too high, a water film will be formed on the surface of activated coke, which will hinder the adsorption of SO2 by activated coke. The initial concentration of SO2 is 700 ppm, the adsorption temperature is 80 °C, the oxygen concentration is 9%, and the concentration of water vapor is 8%. The removal of SO2 by activated coke is better, and the desulfurization rate reaches 97%. [ABSTRACT FROM AUTHOR]

To reduce chemical carbon consumption in activated coke technology used for flue gas purification, the carbon consumption mechanism of commercial activated coke in the presence of water vapor was studied. A fixed-bed reactor and a Fourier transform infrared (FTIR) spectrometer were combined to study the amount of carbon consumption. Temperature-programmed desorption (TPD) coupled with in situ diffuse reflectance infrared Fourier transform (in situ DRIFT) spectra were used to investigate functional group changes of activated coke. The sources and factors influencing carbon consumption in various adsorption atmospheres and in the N2 regeneration atmosphere were compared. Carbon consumption during the adsorption and regeneration process was mainly due to the release of C–O and C=C groups. The addition of H2O increased the formation of carbonates and carboxylic acids during the adsorption process, which decomposed during the regeneration process, thereby increasing carbon consumption. Carbon consumption was reduced during regeneration in an H2O-SO2 adsorption atmosphere, mainly because of the formation of C–S bonds, which reduced the formation of CO2. The C–N bonds generated in an H2O-NO adsorption atmosphere were decomposed during the regeneration process, thereby increasing carbon consumption. In a complex atmosphere of SO2, NO, NH3, and H2O, SO2 was absorbed by NH3, and the amount of carbon consumption was consistent with that in the NO atmosphere during the regeneration process. The total carbon consumption in various adsorption atmospheres ranged from 85.4 to 125.2 μmol/g. Compared with an anhydrous atmosphere, chemical carbon consumption increased by 6.5–14.3% in the presence of H2O. Chemical carbon consumption was reduced by decreasing the H2O concentrations, which provides a reference concept for reducing the operating cost of the activated coke process in industry. [ABSTRACT FROM AUTHOR]

Fine blue-coke and direct liquefaction residue of coal are byproducts in the process of coal chemical production. They were taken as raw materials for the preparation of activated coke by the activation of carbon dioxide. The conditions (activation temperature, activation time and carbon dioxide flow rate) for activated coke preparation were optimized by response surface methodology (RSM). Results showed that activation temperature and activation time had a significant effect on the activated coke iodine adsorption value. The synergistic effect of activation time and carbon dioxide flow had a great influence on iodine adsorption value of activated coke. RSM optimization experiment obtained the optimum activation conditions were activation temperature of 850°C, activation time of 90min and carbon dioxide flow rate of 60 mL/min. Under these conditions, the obtained activated coke iodine adsorption value can reach 401 mg/g, which could meet the needs of industrial desulphurization. [ABSTRACT FROM AUTHOR]

In order to study the mechanism of selective catalytic reduction of activated coke to remove NO in low-temperature flue gas and provide some theoretical basis for the development of related technologies. The pore size distribution and BET specific surface area of AC were obtain by data analyzing of N2 adsorption/desorption isotherm at − 196 °C and carbon matrix and surface chemistry of virgin activated coke samples were characterized by acid–base titration and XPS. The process of selective catalytic reduction of activated coke (AC) samples with NH3 as reducing agent was studied in a fixed bed reactor at 150 °C. The result shows that pore size distribution or BET specific surface of activated cokes have not correlation with denitrification activity for SCR. The NO reduction activities of the activated cokes are apparent to increase with their surface oxygen element content and total amount of acidic sites. Obviously there is good linear relationship between the NH3 adsorption capacity and activity for SCR with linear correlation coefficient 0.943. It has been presented that adsorption of NH3 on acidic functional groups in the edge of large polycyclic aromatic ring of activated coke is key rate controlling step in the SCR heterogeneous catalytic reaction. [ABSTRACT FROM AUTHOR]

• MoCe0.5/AC exhibited high Hg0 removal efficiency at 120 °C. • The adsorption mercury species were identified by Hg-TPD technique. • The mechanism for Hg0 removal was reasonably speculated. • The mechanism on high SO 2 resistance of MoCe0.5/AC was investigated. MoO 3 -CeO 2 /cylindrical activated coke samples (MoCeY/AC) synthesized by an impregnation method were employed to investigate elemental mercury (Hg0) removal at 60–210 °C from simulated flue gas without HCl. MoCe0.5/AC with an optimal Mo/Ce molar ratio of 0.5 exhibited an excellent Hg0 removal efficiency (94.74%) at 120 °C, as well as good stability and prominent resistance to SO 2 and H 2 O. The physicochemical property of the samples and the Hg0 removal mechanism were discussed by ICP-AES, SEM, EDX, BET, XRD, H 2 -TPR, XPS and Hg-TPD. The results of characterizations showed that MoCe0.5/AC possessed the special petal-like outer microstructure, large BET surface area, well-dispersed metal oxides and high reducibility, which was conducive for Hg0 removal. Furthermore, the synergistic effect between Mo6+ and Ce3+ was favorable to the high Hg0 removal performance by providing high valence Ce. According to the Hg-TPD tests, the chemisorption of Hg0 was a major approach for Hg0 removal, while physisorption and catalytic oxidation were just accounted for a tiny fraction. Moreover, the chemisorbed mercury could be validly distinguished into weakly-HgO, strongly-HgO, O α -HgO and HgSO 4 (when SO 2 was added). Compared with raw AC, MoCe0.5/AC could enhance the Hg0 oxidation performance and produce O α -HgO during the Hg0 removal process. In addition, the possible reason for the high SO 2 tolerance of MoCe0.5/AC was examined: (i) the preferential combination between sulfate and MoO 3 could protect CeO 2 for Hg0 removal; (ii) SO 2 could contribute to the formations of weakly-HgO and HgSO 4. Finally, the regenerability of MoCe0.5/AC was also discussed. [ABSTRACT FROM AUTHOR]

• Powdered activated coke was effective for COD removal from real chemical wastewater. • Powdered activated coke exhibited fast adsorption equilibrium within 20 min. • Pilot-scale adsorption experiments verified the effective removal of COD values. • Spent activated coke was successfully regenerated by Fenton oxidation. • Regeneration efficiency was 65.6% after six adsorption-regeneration cycles. Mixed chemical wastewaters in industrial parks contain a large number of non-degradable pollutants, and the advanced treatment process after biological treatment is required to meet the strict discharge requirement. In this study, the cost-effective powdered activated coke was used to remove chemical oxygen demand (COD) from the biological effluent in a chemical wastewater treatment plant in pilot-scale experiments. The powdered activated coke showed higher COD removal than different activated carbons, and the adsorption equilibrium was reached within 20 min. When the initial COD values in the biological effluent were in the range of 140–180 mg/L, the final COD in the treated wastewater decreased to below 80 mg/L with the powdered activated coke dose of 0.609 g/L. Moreover, the spent powdered activated coke was regenerated using Fenton oxidation and reused in the adsorption cycles. The spent activated coke was successfully regenerated at 150 mg/L H 2 O 2 and 1.10 mmol/L Fe2+ at pH 4 for 30 min, and the activated coke still maintained 65.6% regeneration efficiency after six adsorption-regeneration cycles. This study demonstrated that activated coke adsorption was an effective and feasible advanced treatment method for the removal of COD from the mixed chemical wastewaters. [ABSTRACT FROM AUTHOR]

In the process of flue gas purification with activated coke, sulfuric acid and sulfate are deposited on the activated coke surface; therefore, thermal regeneration is needed to recover the activated coke activity, which leads to carbon consumption. In this work, various regeneration parameters, including temperature, time and atmosphere, were investigated to optimize carbon consumption. The experimental results showed that the desulfurization capacity of the activated coke was clearly improved after thermal regeneration, while the denitrification capacity demonstrated no obvious or regular changes. Based on dozens of groups of regeneration experiments, it was found that the chemical carbon consumption per mol SO 2 recovery ranged from 0.5 to 2.0 mol, which was higher than the theoretical value of 0.5 mol. The proportion of CO 2 in chemical carbon consumption ranged from 60%–80% with an average value of 70%, and the rest was CO. According to the results from temperature-programmed desorption (TPD), CO and CO 2 consumption was mainly derived from the decomposition of carboxyl and anhydride groups, with a small contribution from the reduction reaction of sulfuric acid with carbon. CO and CO 2 consumption occupied only 10%–18% of the total carbon-containing functional groups, so the reaction activity was retained after thermal regeneration. The carbon consumption in an NH 3 /N 2 atmosphere was smaller than that in a N 2 atmosphere, which was about half of that in a H 2 O/N 2 atmosphere due to the inhibition of carboxyl group decomposition, based on the results from TPD and in situ diffuse reflectance infrared Fourier transform (In situ DRIFT). Analysis of the thermal regeneration process in four iron and steel factories revealed that the chemical carbon consumption of activated coke accounted for approximately 20%–40% of the total carbon consumption, which was smaller than the contribution from physical carbon abrasion. [ABSTRACT FROM AUTHOR]

A series of Mn–Ni/AC (AC, activated coke) catalysts were synthesized by the impregnation method for the removal of elemental mercury (Hg0) from simulated flue gas. The samples were characterized by BET, ICP-OES, SEM, XRD, XPS, H2-TPR, FT-IR, and TGA. Mn6Ni0.75/AC exhibited optimal removal efficiency of 96.6% in the condition of 6% O2 and balanced in N2 at 150 °C. The experimental results showed that both O2 and NO facilitated Hg0 removal. SO2 could restrain the Hg0 removal in the absence of O2, while the inhibitory effect of SO2 was weakened with the aid of 6% O2. In addition, H2O exhibited a slightly negative influence on Hg0 removal. The characterization of the samples indicated that Mn6Ni0.75/AC possessed larger specific surface area, higher dispersion of metal oxides, and stronger redox ability. In the meantime, the results of XPS and FT-IR demonstrated that the lattice oxygen and chemisorbed oxygen made contributions to Hg0 removal and the consumed oxygen could be compensated by the redox cycle of metal oxides and gas-phase O2. Meanwhile, the mechanisms of Hg0 removal were proposed based on the above studies. [ABSTRACT FROM AUTHOR]

Highlights • Activated coke (AC) with a graphite-like layer crystallite structure as a promising support for metal nanoparticles. • Au nanoparticles supported on AC for efficient catalytic reduction of nitrophenols and azo dyes. • Mechanism of the synergistic effect between Au NPs and AC towards the reduction of nitrophenols. Abstract Activated coke (AC) exhibits excellent properties with a graphite-like layer crystallite structure and possesses mesopore and macropore structures, which can reduce the influence of internal diffusion on the general rate of adsorption and catalytic process greatly. In this work, AC was served as a support for gold nanoparticles (Au NPs) anchoring to prepare Au/AC catalysts via a facile synthesis using ascorbic acid as a mild reducing agent. The morphology and structure of catalysts were characterized by XRD, TEM, FTIR, and XPS analysis. Our experiment results showed that the abundant functional groups on the surface of AC play a vital role in the immobilization of Au NPs. Au/AC was employed as a highly efficient catalyst with a rate constant of 0.1916 s−1 for the reduction of 4-nitrophenols by NaBH 4. Au/AC was also tested for the catalytic reduction of other nitrophenols (2-nitrophenol and 2,4-dinitrophenol) and azo dyes (congo red, methyl orange and erichrome black T), demonstrating that Au/AC exhibited superior catalytic efficiency compared with other Au NPs catalysts. The catalysts showed good reusability, with conversion of 84% in the reduction of 4-NP in 20 s after six cycles. The Au/AC with high TOF has potential to be a workable and efficient catalyst in industrial applications. Present study not only provides a facile preparation route of catalysts using AC as a promising support, but also sheds light on the understanding of mechanism of the synergistic effect between Au NPs and AC towards the reduction of nitrophenols. [ABSTRACT FROM AUTHOR]

In this work, activated coke catalysts were modified with Fe or/and Mn oxides using an impregnation method. The catalysts were thoroughly characterized using various techniques, including XRD, SEM, XPS, TG-DSC and H 2 -TPR. The effects of Fe and Mn oxides modification on the catalytic performance of AC catalysts for simultaneous removal of SO 2 and NO x were studied. The results showed that Fe-Mn/AC catalyst presented excellent catalytic activity for both SO 2 and NO x. The co-doping of Fe and Mn oxides resulted in the formation of the microporous structures, which served as active reaction sites on the catalyst surface. The carbonyl group (C O) was found to play an active role in the oxidation of SO 2 by forming a hydrogen bond, which reduced the energy barrier for the conversion of SO 2 to SO 3. Moreover, it was observed that the deposition of MnSO 4 /FeSO 4 over Fe-Mn/AC catalyst was lower than that of Fe/AC and Mn/AC catalysts. Finally, a possible mechanism model for the denitrification and desulfurization processes over Fe-Mn/AC catalyst was proposed. [Display omitted] • Fe-Mn/AC catalyst exhibited good catalytic ability for SO 2 and NO. • Fe and Mn co-doping was conducive to the formation of AC microporous. • Co-impregnation of Fe and Mn weakened the adsorption of SO 2 on AC. • Mechanism models of Fe-Mn/AC catalyst for de-SO 2 and de-NO were proposed. [ABSTRACT FROM AUTHOR]

It is necessary to research thoroughly on the pyrolysis process of Zhundong lignite coal, in order to simplify the preparation process of activated coke, cut the production cost and improve the utilization of the lignite coal. The pyrolysis characteristics of Zhundong lignite coal were investigated by thermos-gravimetric analysis (TGA) at different heating rates of 10, 20, 30, 40 and 50 °C/min. Meanwhile, two kinds of activated carbons (SC1 and SC2) were respectively prepared at 800 °C by rapid-pyrolysis and temperature-programmed pyrolysis. To obtain the information of char on pore structure parameters, organic functional groups and carbon skeleton structures, the chars were characterized by BET, FT-IR and Raman. Results showed that the variation range of activation energy and pre-exponential factor were 38.89-229.13 kJ/mol and 108.26-1. 18×109 s-1, which were analyzed by TGA data for the pyrolysis of Zhundong lignite coal. The efficiency energy was transmitted to promote the decomposition of organic molecules and produce a large amount of volatile during the pyrolysis process with a heating rate of 30 °C/min. Simultaneously, a reasonable temperature gradient inside the coal char prevented the pore structure blocking caused by thermal condensation reaction. Also, the smooth release of volatiles promoted the formation of pore structure. The char produced by temperature programmed pyrolysis had the specific surface area of 312. 91 m2/g, average pore volume of 0.178 cm3/g and average pore size of 2. 271 nm at a burning-off rate of 46. 5%. The char produced by rapid-pyrolysis had the specific surface area of 424.25 m2/g, average pore volume of 0.189 cm3/g and average pore size of 2. 342 nm at a burning-off rate of 37.3%. A large number of amorphous structures and defect structures were generated in precursor char during the rapid-pyrolysis process, which were conducive to the construction of microporous pore structure at activation stage. [ABSTRACT FROM AUTHOR]